Rubber printing stamp



Aug- 2, 1932. l.. P. SELDEN www@ RUBBER PRINTING STAMP Filed July 2, 1931 Patented Aug. 2, 1932 )STATES lteures rar NT; ortica Louis r. suman, ou RICHMOND, VIRGINIA, AssIGNoR 'ro sAMUEL's. nosnnnonr, or

` RICHMOND, VIRGINIA RUBBER-PRINTING STAMP This invention relates to rubber printing stamps and has special reference to type bases for rubber printing stamps. Y

Rubber printing stamps of the molded class generally are mounted on a wooden or metallic block andthe rubber part consists ofv a rubber base resting against the block and having type molded on its outer face or vulcanized thereto. v

In the older kind of such stamps ber base consisted of a thin sheet of solid rub*- ber but such stamps were found to be defective for obtaining clear impressions if the surfaces on which the impressions were' to he made or if the pressure applied to the stamp Awas `not uniform throughout its contacting surface. Attempts have been made to cure this defect by the use of a base of sponge rubber or the employment of a base having cells formed in its block contacting face. cells have been generally quadrangular in outline,` the cells commonly being parallelograms. It is recognized in all problems involving the rigidity of framed structuresv that a quadrangle is readily distortable.

Consequently it has been found that such bases are apt to yield laterally when pressure is applied vertically to the handle Vof the stamp and that this yielding causes frequent blurring of the impression.

It is the principal object of the present invention to provide an improved cellular base wherein the cells are of such form as to avoid Y any distortion producing blurring while at the same time ensuring evenness of impression and to that end the invention employs triangular cells since the triangle is the only geometrical form which is inherently undistortable and is employed in bridge and roof construction and combinations of parts hereinafter fully described, illustrated in the accompanying drawing and specifically claimed.

In the accompanying drawing like characlthe rub-V Heretoforesuch 1931. Seria1A'Nop548A26. f'

ters of reference indicate like parts in the several views, and:

Figurel is a vertical section through a rub-v ber stamp as constructed in accordance with this invention.

, Figure'2 is a topplan view of onepreferred form of base.

Figure 3 is an enlarged view of a portion of FigureQ. y

Figure Llisa sectionon the linea-4 of Figure 3.

.figure 5 is a view similar to Figure 3 showing one modification of the cells.

Figure 6 Y is a similar view showingV a second modification of the cells.

Figure 7 is a similar view showing athird modiicationof the cells. y

Figure 8 `is a plan of a further modification. i

Figure 9 is FigureS. y

1n the invention as here disclosed there is shown a rubber' stamp having the usual block or headV 10Aprovided with a handle 11 and a section on the line 97--9 of molded type 12.

`the block or head 10 and this base includes a sheet of rubber 13 formingthe under face of the cushion and to which the type sheet is secured. Fromy this sheet rises certain ribs which., in the form shown in Figures 2 and 3 comprise longitudinal ribs 14 and transverse ribs 15 which thus form a seriesrof square cells but diagonal ribs 16 extend across these squares from corner to corner and thus divide each square into four cells the contours of v,which form isosceles triangles.

In the form shown in Figure 5 the diagonal ribs 17 are arranged at angles of 60 to the ytransverse ribs 18 whichpass throughfthe intersections of the diagonal ribs and there may be longitudinal ribs 15. The triangles thus formed are equilateral yand are arranged in rows of interfitting triangles. f

In the form lshown in Figurel 6, each cell 19 is" formed by ribs independent of the ribs of the adjacent cells, the ribs 20 of each cell being arranged in the form of an isoscelesl triangleand four of `thesetriangles being y grouped with their bases at right angles and their apices directed toward each other. Thus the arrangementof each group forms a square somewhat like the arrangement in Figure 3.

he arrangement of Figure 7 yis like that of Figure 6 except that at least two of the triangles are divided into smaller triangles by ribs 2l each running from the apex to the base of one of the large triangles.v A

In each form the freeedges of these ribs vall lie in the saine plane so that the ribs con.-

" evenness of impression is assured.

In Figures 8 and 9 it will be seen that the ribs Q2 are tapered to narrow from their roots upwardly and that adjacent rows of cells are separated by channels 23 formed in the ribs 21 separating those rows.

There has thus been provided a simple and eflicient device of thekind described and for the purpose specified.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the'material spirit thereof. It is not, therefore, desired to confine the invention to the exact form herein shown and described, but itis desired to include all such as properly come within the scope claimed.

Having thus described the invention, what is claimed as new, is:

l. A base cushion for rubberstainps including a sheet of rubber having ribs rising from its upper side and intersecting to form a multiplicity of triangles.

2. A base cushion for rubber stamps formed of soft rubber and having a multiplicity of triangular cells in its upper surface.

3. A base cushion for rubber stamps formed of soft rubber and having a multiplicity of triangular cells in its upper surface, said cells being divided each from each by narrow upstanding ribs.

4. A base cushion for rubber stamps formed of soft rubber and having a multiplicity of triangular cells in its upper surface, said cells being divided each from each by narrow upstanding ribs having their upper edges all in the same plane.

5. A base cushion for rubber stamps including al sheet of rubber having diagonal ribs upstanding from the sheet and intersecting each other throughout the extent of the sheet, and other upstanding ribs passing through certain of the intersections of the diagonal ribs.

6. A base cushion for rubber stamps including a sheet of rubber having diagonal ribs upstanding from the sheet and intersecting each other throughout the extent of the sheet, and other upstanding ribs passing through certain of the intersections of the diagonal ribs both longitudinally and transversely of the sheet to form rectangular groups of triangular cells.

7. A base .cushion for rubber stamps including a sheet of rubber having ribs upstanding therefrom and extending diagonally, longitudinally and transversely of the sheet to form a series of groups of triangular cells, there being four cells in each group and the cells of each group having their base portions at right angles to each other and their apices proximal to the center of the group.

8. A base cushion for rubber stamps including a sheet of rubber having ribs rising from its upper side and intersecting to form a multiplicity of triangles, said ribs tapering to narrow from the sheet upwardly.

9. A base cushion for rubber stamps including a sheet of rubber having ribs rising from its upper side and intersecting to form a multiplicity of triangles, said ribs tapering to narrow from the sheet upwardly, and certain of said ribs having longitudinal channels therein to separate the triangles into rows.

Intestimony whereof I aiwix my signature.

LOUIS P. SELDEN. 

